From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lorenzo Pieralisi Subject: Re: [PATCH V4 3/4] ACPI/IORT: Ignore all errors except EPROBE_DEFER Date: Mon, 22 May 2017 12:31:16 +0100 Message-ID: <20170522113116.GB10449@red-moon> References: <1495119257-26724-1-git-send-email-sricharan@codeaurora.org> <1495119257-26724-3-git-send-email-sricharan@codeaurora.org> <20170522103730.GB7553@red-moon> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Sricharan R Cc: robin.murphy-5wv7dgnIgG8@public.gmane.org, will.deacon-5wv7dgnIgG8@public.gmane.org, joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-arm-msm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, m.szyprowski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org, bhelgaas-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, linux-pci-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-acpi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, tn-nYOzD4b6Jr9Wk0Htik3J/w@public.gmane.org, hanjun.guo-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, okaya-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org, robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, frowand.list-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, sudeep.holla-5wv7dgnIgG8@public.gmane.org, rjw-LthD3rsA81gm4RdzfppkhA@public.gmane.org, lenb-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, catalin.marinas-5wv7dgnIgG8@public.gmane.org, arnd-r2nGTMty4D4@public.gmane.org, linux-arch-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org, j.neuschaefer-hi6Y0CQ0nG0@public.gmane.org, geert-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org, magnus.damm-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org List-Id: devicetree@vger.kernel.org On Mon, May 22, 2017 at 04:35:43PM +0530, Sricharan R wrote: > Hi Lorenzo, > > On 5/22/2017 4:07 PM, Lorenzo Pieralisi wrote: > > Hi Sricharan, > > > > On Thu, May 18, 2017 at 08:24:16PM +0530, Sricharan R wrote: > >> While deferring the probe of IOMMU masters, xlate and > >> add_device callbacks called from iort_iommu_configure > >> can pass back error values like -ENODEV, which means > >> the IOMMU cannot be connected with that master for real > >> reasons. Before the IOMMU probe deferral, all such errors > >> were ignored. Now all those errors are propagated back, > >> killing the master's probe for such errors. Instead ignore > >> all the errors except EPROBE_DEFER, which is the only one > >> of concern and let the master work without IOMMU, thus > >> restoring the old behavior. > >> > >> Fixes: 5a1bb638d567 ("drivers: acpi: Handle IOMMU lookup failure with deferred probing or error") > >> Signed-off-by: Sricharan R > >> --- > >> [V4] Added this patch newly. > >> > >> drivers/acpi/arm64/iort.c | 6 ++++++ > >> 1 file changed, 6 insertions(+) > >> > >> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c > >> index c5fecf9..16e101f 100644 > >> --- a/drivers/acpi/arm64/iort.c > >> +++ b/drivers/acpi/arm64/iort.c > >> @@ -782,6 +782,12 @@ const struct iommu_ops *iort_iommu_configure(struct device *dev) > >> if (err) > >> ops = ERR_PTR(err); > >> > >> + /* Ignore all other errors apart from EPROBE_DEFER */ > >> + if (IS_ERR(ops) && (PTR_ERR(ops) != -EPROBE_DEFER)) { > >> + dev_dbg(dev, "Adding to IOMMU failed: %ld\n", PTR_ERR(ops)); > >> + ops = NULL; > >> + } > >> + > >> return ops; > >> } > >> > > > > It is getting a bit convoluted. Is not it better to propagate the > > error back and let acpi_dma_configure() make a decision accordingly ? > > > > ok, I was trying to keep it in same way as DT, where of_dma_configure > (here acpi_dma_configure) calls of_iommu_configure(here iort_iommu_configure) > which ends up doing the check. So will have to be changed in both places > for symmetry. > > > Something like: > > > > -- >8 -- > > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c > > index e39ec7b..3a10d757 100644 > > --- a/drivers/acpi/scan.c > > +++ b/drivers/acpi/scan.c > > @@ -1371,8 +1371,8 @@ int acpi_dma_configure(struct device *dev, enum dev_dma_attr attr) > > iort_set_dma_mask(dev); > > > > iommu = iort_iommu_configure(dev); > > - if (IS_ERR(iommu)) > > - return PTR_ERR(iommu); > > + if (IS_ERR(iommu) && PTR_ERR(iommu) == -EPROBE_DEFER) > > + return -EPROBE_DEFER; > > In case of other errors apart from EPROBE_DEFER, > iommu = NULL should be set, before passing it on to > arch_setup_dma_ops. Ah yes, sorry, that makes it uglier :( Point is, it does not make sense to me to have of/acpi_dma_configure() check a return code with (IS_ERR()) whilst we know the only error code you are allowed to handle is -EPROBE_DEFER, while at it it is better to make the -EPROBE_DEFER check explicit (otherwise it may seem that of/acpi_dma_configure() can handle an error code that is different from -EPROBE_DEFER - but they don't), no big deal either way though. Lorenzo -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html